UIO-based fault-tolerant control for MASs under arbitrary disturbances and multiple faults

The fault-tolerant consensus problem of multi-agent systems (MASs) under undirected topologies is investigated in this paper, which addresses arbitrary disturbances, multiple faults (including sensor faults and multiplicative as well as additive actuator faults). Firstly, a lumped disturbance combining multiplicative and additive actuator faults and arbitrary disturbances (including unbounded disturbances) is proposed. The accurate estimation and suppression of this lumped disturbance are challenging because it does not satisfy the widely adopted constraints on multiplicative actuator faults and disturbances, namely, having known upper and lower bounds for the multiplicative actuator fault scaling factors and requiring bounded derivatives for the disturbances. Secondly, a novel unknown input observer (UIO) is developed to simultaneously reconstruct the lumped disturbance, system states, and sensor faults. Based on this observer, a innovative UIO-based fault-tolerant control (FTC) strategy is proposed to ensure consensus for MASs. Lastly, simulation results verify the efficacy and merits of the presented approach.